CVE-2026-64620

Severity by source

Trivy's own label is CRITICAL. Rated critical by NVD. Rated lower by Red Hat (high), AlmaLinux (high), Amazon (high), Oracle (high), Rocky Linux (high), Ubuntu (medium).

Description

FreeRDP before 3.28.0 (affected <=3.27.1) contains a heap-based buffer overflow in crypto_rsa_common() (libfreerdp/crypto/crypto.c). The function writes the modular-exponentiation result into the caller's output buffer via BN_bn2bin() and only afterward checks output_length > out_length, so out-of-bounds bytes are written before the bounds check. On the server side, when a client selects RDP Standard Security, the encrypted client random is decrypted into a fixed 32-byte buffer. Because the server publishes its RSA public key, an unauthenticated attacker can forge a ciphertext whose decrypted value is up to the full modulus length (e.g. 256 bytes for RSA-2048), overflowing the 32-byte heap buffer by up to ~224 attacker-controlled bytes pre-authentication, resulting in denial of service.

Affected packages and fixed versions

References

• https://access.redhat.com/errata/RHSA-2026:54486
• https://access.redhat.com/security/cve/CVE-2026-64620
• https://bugzilla.redhat.com/2502752
• https://bugzilla.redhat.com/2502766
• https://bugzilla.redhat.com/2503096
• https://bugzilla.redhat.com/2509985
• https://bugzilla.redhat.com/2510004
• https://bugzilla.redhat.com/2510125